HO CHI MINH (BLOOMBERG) - Vietnam's vast hoard of coffee beans is shrinking, a phenomenon that is set to push rising global prices even higher.

Stockpiles will halve by the end of September from a year earlier, according to the median estimate in a Bloomberg survey of traders. Output from Vietnam, the world's largest robusta supplier and second-largest coffee producer, is also expected to drop in 2022-23.

The dwindling reserves and poor harvest outlook come at a time when global coffee consumption is recovering from a virus-induced slump. Benchmark robusta prices have surged 17 per cent from a 10-month low in the middle of July on supply worries from Brazil to Africa.

Robusta, used by instant coffee makers including Nestle or as a blend in espressos, has been making a comeback. The variety, normally cheaper than arabica, is in strong demand as people look for alternatives to mitigate the impact of rising inflation.

Bean availability in Vietnam has fallen as shipments rose 17 per cent to 1.13 million tonnes in January-July from a year earlier, according to Customs data. The increase in exports has been aided by an improving supply of containers and ships, but may be difficult to sustain given the shrinking stockpiles.

"We are worried" about a shortage through early November, said Quang Minh Coffee Trading chief executive Phan Hung Anh in the southern province of Binh Duong. Local growers are probably holding only around 2 per cent of their annual output, compared with about 13 per cent a year earlier, he said.

The global coffee market is facing one of the biggest deficits in recent memory after drought and frost slashed Brazilian output. Colombia is struggling to recover from crop-damaging rains, while Honduras, Guatemala and Nicaragua are running out of supplies from the 2021-22 harvest. Costa Rica's next-season crop is showing signs of stress, and a drought has cut robusta yields in Uganda.

'Substantial risk'

The slump in Vietnamese inventories pushed domestic robusta prices in Dak Lak province, which accounts for about one-third of the country's harvest, to a record high of 49,100 dong (S$2.92) a kilogram last week.

Carryover stockpiles are seen at 200,000 tonnes at the start of the new season on Oct 1, compared with an estimated 400,000 tonnes a year earlier, according to the survey. Output may fall 6 per cent to 1.72 million tonnes in 2022-23, the survey showed. The robusta variety accounts for about 90 per cent of Vietnam's coffee output.

A drop in the planting area for "profitable" fruit trees and a rise in fertiliser prices will probably affect production in 2022-23, said Mr Do Ha Nam, Intimex Group's chairman and the Vietnam Coffee and Cocoa Association's deputy head.

Citigroup has trimmed its projection for coffee production in Vietnam this year and the next as local crop surveys indicated cherry development had suffered from the lack of fertiliser usage this year. "This poses substantial risk to the prospect for the upcoming planting season," it said in a report earlier this month.